熱處理外文翻譯---偏心軸的熱處理及其力學(xué)性能的研究

1、<p>　　Eccentric shaft heat treatment and mechanical properties research</p><p>　　Abstract This paper focuses on the eccentric shaft material 20Cr heat treatment (carburizing, quenching, a tempering,

2、 and second tempering) process and its main mechanical properties, high hardness is main properties. Analysis how Carburizing temperature ,time an, cooling method ,direct quenching ,a quenching, secondary quenching and o

3、ther factors defect on the mechanical properties and organization from the theory. After confirmed 20Cr's eccentric shaft’s best heat treatment process paramet</p><p>　　ChapterⅠThe introduction</p>

4、<p>　　Preface The role of the eccentric shaft is to adjust the center distance between convenient, eccentric shaft is usually used in the V-belt drive in the planar linkage. Normal shaft can only drive the work

5、 piece, but the eccentric shaft, not only can pass the rotation, also can pass the revolution. Now the U.S. compressor giant Copeland is using eccentric shaft to drive the vortex of revolution and efficient compression f

6、ormulations fast. Eccentric shaft is an important transmission part of el</p><p>　　Schematic diagram of the eccentric shaft</p><p>　　1.2 The purpose of the eccentric shaft and performance requir

7、ements Eccentric shaft is widely used in mining, electromechanical, water conservancy, etc. With the increase in the production of these products, and consumer groups asked the continuous improvement of the quality o

8、f the eccentric shaft is imminent, exported 400 million air-conditioning compressor units by 2008, air exports increased by 27% than in 2005. Air conditioning compressor is exported to South East Asia mainly. Becaus&

9、lt;/p><p>　　1.3 The situation at home and abroad 1.3.1 Domestic Research Trends Heat treatment has a long history in China, with other scientific and technological development, heat treatment technology d

10、evelop the rapidly . (1) Namely, the continuous improvement of experimental methods and techniques. Understanding the relationship between the changes in the organization of metal rules and microstructure, develop new he

11、at treatment process. (2) In the basic theoretical aspects continuously make achie</p><p>　　Recent sessions of the International Conference on Materials and Heat Treatment predicts the development of ancient

12、 and modern metal heat treatment process and heating equipment t, the basic view is: (1) heating equipment In the heating device to more development of electric furnace, especially the development of induction furna

13、ce, reducing fuel furnace. Most of the furnace and heat treatment equipment to achieve automation and digital control, not only can reduce the labor force, but the p</p><p>　　b. expansion of the surface heat

14、 treatment and various types of chemical treatment instead of the whole heat treatment. 1.3.2 Heat treatment equipment and heat treatment technology abroad status          (

15、Ⅰ) in the early 1970s, American Society for Metals (ASM), British Wolf Morrison heat treatment center (Wolfson Heat Treatment Center) and the former Yugoslavia (now Croatia) have established the material and Heat Treatme

16、nt, did it may, according to the database of mechanical performance requi</p><p>　　Vacuum low-pressure carburizing combined with high-pressure gas quenching is an advanced carburizing today, it has carburizi

17、ng speed, excellent carbide organization ,quenching cracking and little deformation, saving energy and carburizing agent raw materials, carburized parts surface quality is good, be helpful for environmental protection e

18、tc. </p><p>　　(Ⅱ) heat treatment equipment: The trend of foreign heat treatment furnace development: (1) stove based on the power is increasing, oil for heat treatment furnace ratio decreasing. (2) To produc

19、t surface quality request more strictly controlled atmosphere heat treatment furnace, this occupies an important position still. (3) Lining tends to use of lightweight materials, the application in resistance furnace wit

20、h heat-resistant component and nonmetallic furnace the proportion of heating elements i</p><p>　　1.4 eccentric shaft failure forms and preventing measures</p><p>　　Shaft loading: fatigue, impact

21、, tensile, compression, bending, twisting, cutting, wear, surface changes, size changes, etching, corrosion and other failure modes. (1) eccentric shaft under heavy load at work, subject to bending stress, wear and tear

22、in the neck, by the main have occurred wear fracture and axial crack two circumstances parts (2) axial crack, axial crack is eccentric shaft parts common failure form, this crack except material adverse outside, main is

23、caused by excessive heat surfa</p><p>　　Chapter II Theoretical analysis</p><p>　　2.1 Heat Treatment of eccentric shaftUnified Digital Code: A20202【Chemical Composition】 ⑷ (mass fraction) (%)&l

24、t;/p><p>　　C: 0.18~0.24Si: 0.17~0.37M n: 0.50~0.80Cr: 0.70~1.00</p><p>　　【Mechanical properties 】Sample blank size (mm): 15 Heat buried: The first quenching temperature: 880 ℃; Coolant: water

25、, oil The second quenching temperature: 780 ~ 820 ℃; Coolant: water, oil Tempering heating temperature: 200 ℃; Coolant: water, air Tensile strength ≥ 835MPa Yield point: ≥ 540MPaLaSalle epigastria long rate: ≥ 10%

26、Section shrinkage: ≥ 40% Shock absorption≥ 47J impact energy Brinell hardness (annealed or high temperature tempering state): ≤ 179 </p><p>　　【Main Special items】 </p><p>　　Compared with

27、the 15Cr steel , it has higher strength and its quench-hardening ability in oil critical quenching, up to 4 ~ 22mm diameter appearing in water to critical quenching of 11 ~ diameter 40mm lottery, but the firmware is poor

28、, when the steel carburizing Grains are still growing tendency, when the direct quenching temperature on impact toughness of greater impact, so the secondary quenching after carburizing need to improve the toughness of t

29、he Ministry of parts heart, no temper brittlen</p><p>　　【examples Of Application】 </p><p>　　This kind of steel is used mostly manufacturing hea

30、rt the demand is higher, intensity of surface bear wear, section 30mm below in complex shape and load or small carburized parts (oil quenching machine), such as: transmission gear, gear axle, CAM, worm, etc. For small an

31、d high heat treatment deformation wear parts, carburizing should high-frequency surface after quenching, such as modulus is less than 3 gear wheel, bearing etc. 20Cr can also be used in conditioning condition, used to ma

32、ke the sp</p><p>　　Chapter Ⅲexperimental materials and experimental methods</p><p>　　3.1Materials: Material for this study is the eccentric shaft 20Cr, 20Cr is the carbon content of 0.2% for the

33、 carburization of low carbon steel, 20Cr steel than carbon steel carbon content of the same strength and hardenability were clearly high, oil quenching to the semi-martensitic hardenability of hardness for the φ20 ~ 23mm

34、. Compared with the 15Cr steel has high strength and hardenability, the critical quenching diameter, oil is about 4-22mm, the water is about 11-40mm, poor toughness, good </p><p>　　3.2 Experiment:The heat t

35、reatment process in this experiment were as follows:3.2.1 installed furnace: the axis (cleaning) vertically into the basket mesh, large hole down, plug hole facing up gambling sales, in the installed furnace, put a patt

36、ern into the end of the eccentric shaft basket. Will be installed for the work piece material into the furnace basket hanging clothes time to close the lid, tighten the lid bolts, drops of methanol, the fans, transmissio

37、n temperature, into the exhaust pe</p><p>　　3.2.2 Exhaust: ≤ 880 ℃ installed outside the pattern 2, the amount of methanol drops of 180-200 drops / min; 880-920 ℃ stop drops of methanol, the drops of kerose

38、ne, kerosene drop volume 180-200 drops / min; 910 \ 920 ℃, 30 minutes, the amount of kerosene drops of 180-200 drops / min; Close 30 minutes after the temperature pattern holes, Exhaust flame length of 80 ~ 150mm, int

39、o the carburizing period.</p><p>　　3.2.3 carburization of 910 ~ 920 ℃, 180 points, the amount of kerosene drops of 180-200 drops / min; water column 30 ~ 60mm.3.2.4 Diffusion Cooling: ≥ 0.6mm deep diffusion

40、 layer, it can spread into the cool, adjust the volume of kerosene drops of 100 to140 drops / min, 10 to 30mm water column.3.2.5 released air.</p><p>　　3.4. Metallographic specimen preparation, according t

41、o the microstructure and hardness gradient measurements3.4.1 The preparation phase include microscopic pattern sampling, grinding, polishing, etching and other processes.Sampling pattern should be selected according to

42、 purpose of the study, whichever is representative of the site....</p><p>　　Grinding Cut in the grinding machine polished style, pointed to rounding. Then 180 ℃, 240 ℃, 300 ℃ and 600 ℃ grit polishing clo

43、th, and back with 800 ℃, 1500 ℃ progressively metallographic sandpaper grinding, grinding to 2000 ℃ has been rough sandpaper before polishing and fine polishing .Grinding style, each for a grinding step (i.e. for-One sa

44、ndpaper), the style should be turned 90 degrees the direction of grinding. It will show the wear scar is rubbed off. No abrasive cloth in each style </p><p>　　Polishing The pattern needs to be polished f

45、inely ground. The purpose of polishing is to remove the legacy of fine grinding fine when worn to obtain bright mirror. Style is polished on the polishing machine specific, and speed like 100 ~ 150r/min. Polishing disk p

46、olishing spread when there are velvet and other fabrics, and continue to drip slurry. Polishing or Mg0 by Cr203 abrasive and a very fine-grained water suspension formed, relying on the polishing slurry in the fine grindi

47、ng powder an</p><p>　　Erosion The pattern has been polished before etching must be observed under the microscope. Erosion is mainly dependent on the metal etchant solution or electrochemical corrosion pr

48、ocess, the surface of the metal pattern and the composition of grain and grain boundary phases present between the slightly uneven, under the microscope can be clearly observed on the style surface, etching time should b

49、e appropriate, the general pattern can be grinding halt when dark. If lack of repeated erosion.</p><p>　　顯示對(duì)應(yīng)的拉丁字符的拼音</p><p><b>　　字典</b></p><p><b>　　朗讀</b>&l

50、t;/p><p>　　顯示對(duì)應(yīng)的拉丁字符的拼音</p><p><b>　　字典</b></p><p>　　朗讀顯示對(duì)應(yīng)的拉丁字符的拼音</p><p><b>　　字典</b></p><p>　　In recent years, micro hardness measuri

51、ng the hardness of commonly used equipment. Hardness is measured by reading down micro hardness. The focusing mechanism, measuring microscope, loading bodies, correct choice of load, speed automatic loading Unloading Tes

52、t force control of test force and the proper time, the optical amplification by micro hardness, measured in a certain test .Force of diamond pyramid indenter pressed into the measured object left after the diagonal lengt

53、h of indentation, to </p><p>　　4.1 The hardness of the experiment</p><p>　　Surface hardness HRC62.3, the minimum hardness of heart HRC27.2 the Ministry of the eccentric shaft has reached the per

54、formance requirements, and the Ministry of hardness from the surface to the heart decreases in line with the surface of high hardness, high wear resistance of the heart has good strength and toughness of the Department o

55、f requirements. The following figure is the hardness, the distance between the Ministry of centrifugation: Figure on the display and hard cover table further</p><p>　　Spacing is 0.25mm</p><p&g

56、t;<b>　　朗讀</b></p><p>　　顯示對(duì)應(yīng)的拉丁字符的拼音</p><p><b>　　字典</b></p><p><b>　　朗讀</b></p><p>　　顯示對(duì)應(yīng)的拉丁字符的拼音</p><p><b>　　字典<

57、;/b></p><p><b>　　朗讀</b></p><p>　　顯示對(duì)應(yīng)的拉丁字符的拼音</p><p><b>　　字典</b></p><p>　　tttTTTKkk 朗讀顯示對(duì)應(yīng)的拉丁字符的拼音</p><p>　　4.2 Metallographic

58、 analysis and discussion Through the above process and experimental results, we can get the 20Cr eccentric axis of the heart obtained after carburizing Department of 27HRC-32HRC hardness and surface hardness 59 ~ 63H

59、RC, which can guarantee the eccentric shaft has good wear-resistant surface Resistance, high strength and center better plasticity and toughness, while maintaining a core part of the impact resistance of high capacity, i

60、t reached the surface carburization purpos</p><p>　　We know that the surface carburization treatment is to carbon content of 0.1% -0.25% of the steel on the carbon potential of the medium to high, by having

61、high activity of carbon atoms diffuse into the steel within a certain thickness of the carbon content is higher The carburized layer, and then quenched \ tempering, the surface of the work piece by high carbon content la

62、yer M, and the Ministry for the heart to maintain the original concentration of carbon content in the carbon content of low M</p><p>　　Surface structure (high-carbon tempered marten site + residual austenite

63、 + carbide)</p><p><b>　　朗讀</b></p><p>　　顯示對(duì)應(yīng)的拉丁字符的拼音</p><p><b>　　字典</b></p><p>　　Filter layer (marten site + retained austenite)</p><

64、p>　　Ministry of the heart (low-carbon tempered marten site)</p><p>　　Obtained by the above microstructure picture we can see on the eccentric shaft to the surface after carburizing treatment are high-carb

65、on marten site or acicular marten site, the needle is usually in the high-carbon marten site steel and iron-nickel alloy to form - the typical marten site. For low carbon steel, carbon content in less than 1.0%, and the

66、coexistence of marten site, the carbon content of only 1.0% higher than when alone. It is a two-dimensional shape of convex lens sheet, compared </p><p>　　In mind we can see by the Ministry of the main organ

67、ization for low-carbon marten site, which marten site mainly in low, medium carbon steel, as well as margin steel, stainless steel, iron-nickel alloy. Features for each unit of the organization for the narrow and elongat

68、ed shape of the slab, and many of the strip is always parallel to each other in groups together, it is also known as lath marten site, the structure of its sub-bit Wrong, it is also known dislocation marten site.</p&g

69、t;<p>　　Eccentric shaft over the surface of the carbon content Pie, so get organized after quenching is mainly acicular marten site, the higher its hard-line level, but the plasticity and toughness on the poor, an

70、d heart Ministry of carbon area, it obtained after quenching Lath marten site of the main organizations. But the plasticity and toughness better than the needle-like marten site, the main reason for the sub-structure of

71、lath marten site and dislocation in the carbon zone decision. So be on the </p><p>　　This material is 20Cr on the eccentric axis: → quenching → ??cementite after tempering microstructure analysis: Part fr

72、om the surface after carburizing quenching the basic structure of the Ministry Chitin are: marten site + carbide + retained austenite → marten site and marten site → austenite → marten site carbon core part.</p>&

73、lt;p>　　Carburizing the most part the highest concentrations of carbon surface, the microstructure of pearlite and a small amount of network carbide (). Carburized layer in an appropriate amount of granular carbide dis

74、tributed in hidden needle (or needle) shape uniformly. Ministry of the heart is not the organization of raw materials, parts carburized zone area, the lath marten site, not too many massive ferrite composition. Infiltra

75、tion layer as follows: needle plate marten site, dispersed a small amo</p><p>　　1. carburizing the most part the highest concentrations of carbon surface, the microstructure of pearlite and a small amount of

76、 network carbide (), carburized layer in an appropriate amount of granular carbide uniformly distributed in hidden needle (or needle) shape . Surface hardness is HRC62.3. 2. Excessive level of carbon content of about 0

77、.77%. By the amount of lath marten site and acicular marten site formed.3. Heart Ministry is not the organization of raw materials, parts carburized zon</p><p>　　Chapter V Conclusion</p><p>　　I

78、n the experimental study of the eccentric shaft 20Cr material used for the carburizing heat treatment and mechanical properties of tissue has an important effect. Carburizing time and depth all affect the hardness of the

79、 subsequent quenching by analyzing the shape of the eccentric shaft and the resulting mechanical properties must be pre-heat treatment process, so that the eccentric shaft with an appropriate microstructure, good mechani

80、cal performance. Studies in different carburizing heat trea</p><p>　　偏心軸的熱處理及其力學(xué)性能的研究</p><p><b>　　摘要</b></p><p>　　本文著重研究了材料為20Cr的偏心軸的熱處理（滲碳、淬火、一次回火、二次回火）工藝及其高硬度為主的力學(xué)性能。從

81、理論上分析滲碳溫度、時(shí)間和冷卻方式直接淬火、一次淬火、二次淬火等因素對(duì)力學(xué)性能、組織的影響。確定了材料為20Cr的偏心軸的最佳熱處理工藝參數(shù)和最佳滲碳淬火方式（鹽浴、直接淬火、低溫回火）后進(jìn)行對(duì)滲碳后滲層深度、金相組織及力學(xué)件能的檢測(cè)與分析。</p><p>　　關(guān)鍵詞：偏心軸、熱處理、滲碳、滲碳溫度、冷卻方式、滲碳層第一章緒論</p><p><b>　　1. 1前 言<

82、;/b></p><p>　　偏心軸的作用是為了方便調(diào)節(jié)軸與軸之間的中心距，偏心軸通常運(yùn)用在平面連桿機(jī)構(gòu)三角帶傳動(dòng)中。一般的軸，只能帶動(dòng)工件自轉(zhuǎn)，但是偏心軸，不但能傳遞自轉(zhuǎn)，同時(shí)還能傳遞公轉(zhuǎn)?，F(xiàn)在美國(guó)的壓縮機(jī)巨頭Copeland就是用偏心軸來帶動(dòng)渦旋公轉(zhuǎn)從而快速高效的壓縮制劑的。偏心軸是電動(dòng)工具電錘的重要傳動(dòng)零件。安裝偏心軸就是靠它的慣性作用讓機(jī)器在運(yùn)轉(zhuǎn)到死點(diǎn)位置不會(huì)產(chǎn)生鎖機(jī)。最常見的例子就是：家用縫紉機(jī)腳

83、動(dòng)驅(qū)動(dòng)輪的運(yùn)轉(zhuǎn)。偏心軸帶動(dòng)機(jī)器的轉(zhuǎn)動(dòng)，是機(jī)械制造中不可少的零件。</p><p><b>　　偏心軸結(jié)構(gòu)示意圖</b></p><p>　　1.2偏心軸的用途及性能要求</p><p>　　偏心軸在采礦、機(jī)電、水利等方面的應(yīng)用極為廣泛，隨著這些成品產(chǎn)量的增加以及消費(fèi)人群要求的不斷提高，偏心軸質(zhì)量的提髙也迫在眉睫。截止2008年我國(guó)共出口空調(diào)壓縮

84、機(jī)400萬臺(tái)，比2005年出口空調(diào)壓縮機(jī)同期增長(zhǎng)27%?？照{(diào)壓縮機(jī)出口地區(qū)以東南亞為主。</p><p>　　因?yàn)槠妮S在工作時(shí)承受巨大的沖擊載荷，而且電錘的工作環(huán)境惡劣、多粉塵，零件易磨損。所以要求偏心軸表面具有髙的硬度、耐磨性及疲勞強(qiáng)度，而心部則具有一定的強(qiáng)度和良好的塑性、韌性等的特殊性能。1.3國(guó)內(nèi)外的現(xiàn)狀1.3.1國(guó)內(nèi)研究動(dòng)態(tài)</p><p>　　我國(guó)熱處理工藝歷史悠久，隨其它

85、科學(xué)技術(shù)的發(fā)展，熱處理技術(shù)得到迅速的發(fā)展。即，（1）實(shí)驗(yàn)手段和技術(shù)的不斷完善。對(duì)金屬中的組織轉(zhuǎn)變規(guī)律及組織與性能之間的關(guān)系不斷了解，進(jìn)而發(fā)展新的熱處理工藝。（2）在基礎(chǔ)理論方面不斷取得成就。(3)表面化學(xué)的研究，發(fā)展了各種表面防護(hù)熱處理及表面強(qiáng)化熱處理。（4）其它新能源，新技術(shù)的開發(fā)，使熱處理工藝成為許多復(fù)合的工藝。</p><p>　　最近幾屆國(guó)際材料及熱處理會(huì)議上對(duì)古今金屬材料熱處理工藝和加熱設(shè)備的發(fā)展作了預(yù)

86、測(cè)，基本看法是：(1)加熱設(shè)備</p><p>　　在加熱設(shè)備中要更多地發(fā)展電爐，特別發(fā)展感應(yīng)加電爐，減少燃料爐。大多數(shù)加熱爐和熱處理設(shè)備要實(shí)現(xiàn)自動(dòng)化及數(shù)字控制，這不僅可以減少勞動(dòng)力，而且是提高熱處理質(zhì)量的前提。(2)熱處理工藝</p><p>　　a.改進(jìn)常規(guī)加熱工藝?？諝饧訜釋⒈徽婵占訜?，控制氣氛或保護(hù)氣氛加熱，以及真空和控制氣氛聯(lián)合加熱所取代。隨著真空技術(shù)的進(jìn)步，真空熱處理向著提

87、高爐子工作溫度，自動(dòng)化方向發(fā)展。感應(yīng)加熱熱處理，趨向與增大功率及擴(kuò)大頻率范圍方向發(fā)展。 b.擴(kuò)大表面熱處理及各類化學(xué)熱處理代替整體熱處理。1.3.2 國(guó)外熱處理設(shè)備及熱處理技術(shù)現(xiàn)狀</p><p>　　(Ⅰ)在七十年代初，美國(guó)金屬學(xué)會(huì)(ASM)、英國(guó)的沃爾夫遜熱處理中心(Wolfson Heat Treatment Center)以及原南斯拉夫(現(xiàn)克羅地亞)都相繼建立了材料與熱處理數(shù)據(jù)庫(kù)，做到了可以根據(jù)零

88、件熱處理后力學(xué)性能要求進(jìn)行計(jì)算機(jī)輔助選材，或已知材料和熱處理工藝預(yù)見最后的組織和性能。隨后歐美、日本等先進(jìn)工業(yè)國(guó)家開發(fā)出用計(jì)算機(jī)對(duì)各種熱處理工藝過程的控制技術(shù)，開展了計(jì)算機(jī)控制下的工藝參數(shù)數(shù)?？刂萍夹g(shù)研究，并在生產(chǎn)中獲得了應(yīng)用。目前國(guó)際知名廠家的許多連續(xù)式和周期式熱處理生產(chǎn)線都采取了用可編程控制器(Programable Controller)或微處理機(jī)的單控或群控。國(guó)外的熱處理廠家非常重視熱處理過程中的冷卻。根據(jù)產(chǎn)品的技術(shù)和工藝要求，

89、可進(jìn)行快速冷卻、油淬冷卻、一次性氣淬冷卻等。以前采用氣淬方式冷卻的淬火氣體有氮?dú)?、氦氣等，現(xiàn)在用空氣強(qiáng)烈噴射，使工件在極快速度下冷卻，淬火后表面僅有極薄的氧化色膜，呈灰白色，零件色彩依然美觀，而節(jié)約大量氮?dú)夂投栊詺怏w，使熱處理成本進(jìn)一步下降。</p><p>　　真空低壓滲碳與高壓氣淬相結(jié)合是當(dāng)今一種先進(jìn)的滲碳淬火工藝，它具有滲碳速度快、碳化物組織優(yōu)良、淬火開裂和變形小、節(jié)約能源和滲碳劑原料、滲碳零件表面質(zhì)量好、

90、有利于環(huán)保等特點(diǎn)。</p><p>　　(Ⅱ)熱處理設(shè)備：國(guó)外熱處理爐的發(fā)展趨勢(shì)：（1）以電能為熱源的爐子增多，熱源為煤氣的熱處理爐比例逐漸減少。（2）對(duì)產(chǎn)品表面質(zhì)量的要求更為嚴(yán)格，可控氣氛熱處理爐仍占重要地位。（3）爐襯趨向使用輕質(zhì)材料，在電阻爐上應(yīng)用非金屬爐用耐熱構(gòu)件和發(fā)熱元件的比例逐漸增加。（4）微機(jī)和可編程序控制器的發(fā)展加速了熱處理自動(dòng)化，并有與其它工序組成全自動(dòng)熱處理線的趨勢(shì)。</p>&

91、lt;p>　　1.4偏心軸的失效形式及其防止措施</p><p>　　軸類載荷：疲勞、沖擊、拉、壓、彎、扭、切、磨損、表面變化、尺寸變化、咬蝕，腐蝕等失效形式。（1）偏心軸在工作時(shí)承受巨大的沖擊載荷、受到彎曲應(yīng)力，除頸部發(fā)生磨損外，主要有斷裂及軸向裂紋兩種情況零件（2）軸向裂紋，軸向裂紋也是偏心軸零件常見的失效形式，此種裂紋除材質(zhì)不良外，主要是熱處理不當(dāng)引起的淬透性過大引起表面拉應(yīng)力，由于合并部分周向表面拉

92、應(yīng)力大于軸向表面拉應(yīng)力，且材料的橫向性能低于縱向的，防止此類失效也應(yīng)從熱處理工藝方面解決，控制零件的淬硬層深度，并及時(shí)進(jìn)行回火。（3）軸的失效形式：主要有因疲勞強(qiáng)度不足而產(chǎn)生的疲勞斷裂、因靜強(qiáng)度不足而產(chǎn)生的塑性變形或脆性斷裂、磨損、超過允許范圍的變形和振動(dòng)等。（4）軸類的斷裂主要是扭轉(zhuǎn)疲勞斷裂。</p><p><b>　　第二章理論分析</b></p><p>　　

93、2.1偏心軸的熱處理統(tǒng)一數(shù)字代號(hào)：A20202</p><p>　　【化學(xué)成分】⑷（質(zhì)量分?jǐn)?shù)）（%）C: 0.18~0.24Si: 0.17~0.37Mn: 0.50~0.80Cr: 0.70~1.00</p><p><b>　　【力學(xué)性能】</b></p><p>　　試樣毛坯尺寸（mm）：15熱處埋：</p>&

94、lt;p>　　第一次淬火加熱溫度： 880℃；冷卻劑 ：水、油第二次淬火加熱溫度： 780?820℃；冷卻劑：水、油回火加熱溫度：200℃；冷卻劑：水、空抗拉強(qiáng)度≥835MPa</p><p>　　屈服點(diǎn)：≥540 Mpa</p><p>　　斷后伸長(zhǎng)率:≥10%斷面收縮率:≥40%</p><p><b>　　沖擊吸收功≥47J</b

95、></p><p>　　布氏硬度 （退火或髙溫回火狀態(tài)）：≤179</p><p><b>　　【主要特件】</b></p><p>　　與15Cr鋼相比，有較高的強(qiáng)度及淬透性，在油中臨界淬透直徑達(dá)4~22mm，在水中臨界淬透直徑達(dá)11?40mm，但韌件較差，此鋼滲碳時(shí)晶粒仍有長(zhǎng)大傾向，降溫時(shí)直接淬火對(duì)沖擊韌性影響較大，所以滲碳后需二次淬

96、火以提高零件心部韌性，無回火脆性；鋼的冷應(yīng)變塑性高，可在冷狀態(tài)下拉絲；可切削性在髙溫正火或調(diào)質(zhì)狀態(tài)下良好，但退火后較差；焊接性較好，焊后一般不需熱處理，但厚度大于15mm的零件在焊前需預(yù)熱到100?150℃。</p><p><b>　　【應(yīng)用舉例】</b></p><p>　　這種鋼大多用于制造心部強(qiáng)度要求較高，表面承受磨損、截面在30mm以下的或形狀復(fù)雜而負(fù)荷不大

97、的滲碳零件(油淬)，如：機(jī)床變速箱齒輪、齒輪軸、凸輪、蝸桿等；對(duì)熱處理變形小和高耐磨性的零件，滲碳后應(yīng)進(jìn)行高頻表面淬火，如模數(shù)小于3的齒輪、軸等。20Cr也可在調(diào)質(zhì)狀態(tài)下使用，用于制造工作速度較大并承受中等沖擊負(fù)荷的零件，這種鋼還可用作低碳馬氏體淬火用鋼，更進(jìn)一步增加鋼的屈服強(qiáng)度和抗拉強(qiáng)度。</p><p>　　第三章實(shí)驗(yàn)材料及實(shí)驗(yàn)方法</p><p><b>　　3.1材料：&

98、lt;/b></p><p>　　本文研究的是材料為20Cr的偏心軸，20Cr是碳含量為0.2%的低碳鋼適合進(jìn)行滲碳處理，20Cr鋼比相同含碳量的碳素鋼的強(qiáng)度和淬透性都明顯地高，油淬到半馬氏體硬度的淬透性為φ20~23mm。與15Cr鋼相比，有較高的強(qiáng)度及淬透性，臨界淬透直徑 ，油中約為4-22mm，水中約為11-40mm，韌性較差，焊接性較好，焊后-般不需熱處理。用途：大都用作滲碳鋼，適用于制造心部強(qiáng)度要

99、求較高，表面承受摩擦，截面尺寸在30mm以下或形狀復(fù)雜而載荷不大的滲碳件（油淬），如機(jī)床變速箱齒輪，齒輪軸，凸輪，蝸桿等，對(duì)要求熱處理變形小和高耐磨性的零件，滲碳后可進(jìn)行高頻表面淬火，如模數(shù)≤3mm的齒輪，軸和花鍵軸等。此外，也可在調(diào)質(zhì)狀態(tài)下使用，用于制造工作速度較大并承受中等沖擊載荷的零件。</p><p>　　這種鋼淬火低溫回火后具有良好的綜合力學(xué)性能，低溫沖擊韌性良好，回火脆性不明顯。滲碳時(shí)鋼的晶粒有長(zhǎng)大傾

100、向，所以要求二次淬火以提高心部韌性，不宜降溫淬火。當(dāng)正火后硬度為HB170~217時(shí)相對(duì)切削加工性約為65%，焊接性中等，焊前應(yīng)預(yù)熱到100?150℃，冷變形時(shí)塑性中等。</p><p>　　3.2 實(shí)驗(yàn)內(nèi)容：本次試驗(yàn)的熱處理工藝如下：</p><p>　　3.2.1裝爐：將軸（清洗）垂直插入筐篩孔，大孔向下，小孔朝上插賭銷，在裝爐時(shí)，將一個(gè)偏心軸式樣裝入底筐內(nèi)。將裝好工件的料筐衣次吊入